Lengthy hormone therapy tied to cancer risk-study

CHICAGO, May 9 (Reuters) Women who take estrogen-only hormone replacement therapy for 20 years or longer to treat symptoms of menopause have a higher risk of developing breast cancer, researchers have said.

The risk of breast cancer from estrogen therapy increased with long-term use by women who had a hysterectomy but did not become significant until after two decades of use.

The study noted some women take estrogen for long periods to ward off ailments associated with aging, like osteoporosis, and they might want to look for alternatives.

''Women who take estrogen therapy for prevention or treatment of osteoporosis typically require longer-term treatment and should thus explore other options, given the increased risk of breast cancer with longer-term use,'' wrote study author Wendy Chen of Brigham and Women's Hospital.

In 2002, alarming findings released early from the Women's Health Initiative study linked hormone therapy with increased risks of ailments including stroke, blood clots and breast cancer.

Since then, however, there have been confusing findings that portrayed the therapy as alternately harmful or helpful, depending on the women's age, time of menopause, length of use, and other factors.

In general, hormone therapy is now prescribed at the lowest possible dose for the shortest period of time, a strategy backed by Wyeth, the maker of market-leading drugs Premarin and Prempro.

Estrogen therapy is made from pregnant horse urine. Some women have sought natural alternatives, like soybean extract, which might mimic the estrogen therapy.

In the study published in the Archives of Internal Medicine, a journal published by the American Medical Association, Chen examined data from the Nurses' Health Study, beginning with 11,500 female nurses in 1980 who had a hysterectomy, and ending with nearly 29,000 nurses. A hysterectomy removes all or part of the uterus.

Women who have not had a hysterectomy but want relief from menopausal symptoms like hot flashes take a combination of estrogen and progestin, which is designed to prevent uterine cancer. The combination therapy is associated with a higher risk of breast cancer even when taken for a shorter duration.

In the current study, a woman's relative risk of breast cancer after less than 10 years of estrogen-only therapy was slightly under 1.00, meaning there was neither a statistically significant higher nor lower risk of the disease. After 10 to 15 years of use the risk rose to a still insignificant 1.06, but it jumped to a significant 1.42 after 20 years of therapy.

The association between hormone therapy and breast cancer was strongest for tumors with receptors that responded to estrogen or progestin, as in previous studies.

Reuters DKS GC0844